Method

First remove the pastry from the fridge and let it come to room temperature (about 10 minutes).

Meanwhile, wash the asparagus in cold water, then take each stalk in both hands, and bend and snap off the woody end. Then, arrange the stalks in an opened fan steamer. Place the steamer in a frying pan or saucepan, pour in about 1 in (2.5 cm) of boiling water from the kettle, then add some salt, put a lid on and steam for 2-3 minutes, or until they feel tender when tested with a skewer.

After that, remove them from the steamer and allow them to cool. Then dry the stalks with kitchen paper and cut each one into 3, on the diagonal. Next, using a small sharp knife, remove the rind from the Fontina or Gruyère and cut it into ½ in (1 cm) cubes.

Then, in a small bowl, mix the Parmesan and crème fraîche and add some salt and freshly milled black pepper. Now carefully unroll the sheet of pastry onto a lightly floured work surface and cut it in half. Roll out one half until it measures 12 x 12 in (30 x 30 cm) and then cut that into 4 squares measuring 6 x 6 in (15 x 15 cm) . Then repeat the rolling and cutting with the other piece of pastry, so you end up with 8 squares in all.

Beat the egg yolks with the milk. Next, you need to carefully brush the edges of 4 of the pastry squares with this mixture. Then divide half of the crème fraîche filling between these 4 pieces of pastry, spooning about a level dessertspoon into the centre of each square.

Next, lay about half the quantity of asparagus on top of the crème fraîche, with several cubes of cheese tucked in-between. Now pull up the opposite corners of each square to meet in the centre like an envelope. Carefully pinch the seams together to seal them, and make a small hole in the centre of each one to allow the steam to escape. Then, using a fish slice, transfer the parcels to the baking tray and now make the other 4.

Once you have made 8 parcels, cover them with clingfilm and chill until you are ready to cook them.

Preheat the oven to gas mark 6, 400°F (200°C). Then, brush each one with some of the remaining beaten-egg mix and lightly sprinkle each one with some Parmesan. Bake on a high shelf in the oven for 20-25 minutes or until they are golden brown, and serve them straightaway, garnished with a few sprigs of watercress.